The flooring manufacturer installation guidelines typically call out specific moisture testing requirements. The requirements will vary depending on the flooring manufacturer. Some state to conduct testing in accordance with ASTM F1869 (CaCl) and/or ASTM F2170 (rapidRH), others may use solely and meaning both test methods.

I believe there are many instances where ASTM F1869 requriements will be met but the F2170 results will be too high. For instance, the CaCl result will be under 5 lbs. and relative humidity will be at 85% exceeding the required 80%.

In an and/or typr guideline does the flooring contractor install the flooring with a typical warrenty?

There are slip sheet products.
We have another product that can be installed up to 92%.

Many adhesive systems claim to handle 85%. Again, depends on the product. However, I have never seen any Adhesive system manufacturer stand behind a moisture failure. If you look closely enough you can almost always find a structural issue. I've only seen long run problems with the 'miracle adhesives'.... SO FAR.

Hey that Koster is good stuff... We have a fantastic Koster installer on the forums here.. The guy REALLY knows his stuff....

Okay, seriously 99% rH is easy to remedy. Not cheap, but easy. Kind of like me I'm punchy today, don't know why... Maybe losing my rear in the market is taking its toll....

Anyway, testing using 1869 is really scary and the reason the industry is RUNNING from the test is that it shows only the top 1/4" or so of the concrete and does not give a complete picture of the slab's potential for a moisture related failure.

For instance, a burned lightweight slab may read 3 lbs MVER yet still be at 98% rH. Covering that slab with a moisture sensitive flooring would be a risk because as that slab ages the moisture inside the slab will equilibrate and move through the slab taking alkaline products with it. Years later you can open a failure and find a wet highly alkaline concrete surface destroying the flooring.

Many flooring installers have also placed floors on low MVER slabs only to find the sub-slab vapor retarder was missing or damaged and the moisture level increased over time.

The rH test was created to be a much better indicator of slab moisture. Looking inside the slab helps show us trapped moisture in and under the slab that the CaCl test could never reveal. I wish I had a nickel for every time I had an installer tell me the slab WAS dry, and now it's wet and they have no idea where the water came from.... Usually it was there all the time, we just need to use a test that shows it.

In my area of installation (residential) there is no history of sub-slab vapor retarder so my take is that there is none. I take into account grading and runoff from the roof along with moisture tests to help me decide what action to take. It's usually always a topical trowel on vapor retarder just for insurance sake.